1. Field of the Invention:
The present invention is directed to a compound obtained by the reaction of allantoin with formaldehyde. The compound exhibits activity against bacteria, mold and yeast and hence is useful as a preservative for products susceptible to microbial contamination.
2. Description of the Prior Art:
U.S. Pat. No. 3,248,285 described a series of compounds prepared by condensing allantoin with formaldehyde which exhibit bacteriostatic and/or bactericidal activity. Because of this activity, the compounds are effective as preservatives in cosmetics and other products susceptible to bacterial contamination. However, since cosmetics and most other perishable products are subject to contamination by yeast and mold as well as bacteria, the compounds must be used in combination with other preservatives which are effective against yeast and mold. Such preservatives are typically referred to as antifungal agents.
Generally, the parabens, i.e., esters of p-hydroxybenzoic acid, are used as the additional preservative components which provide protection against yeast and mold. Although the combination of parabens with the aforementioned bacteria-combating compounds works well and is widely used in the cosmetic industry, it presents certain heretofore unsolved problems. In particular, the parabens, as well as a great many other antifungal agents, are easily inactivated or deactivated. Inactivation of parabens and like compounds may be attributed to several factors including the migration of the compounds from the aqueous phase of an emulsion to the oil phase, the binding of the compounds by commonly used nonionic emulsifiers, and/or the interfering effect of other components in the product sought to be protected. Inactivation is particularly acute in cosmetics since nonionic emulsifiers inactivate anti-fungal agents and are common ingredients in cosmetic emulsions such as creams and lotions. Thus, cosmetic formulators are often unable to adequately preserve such emulsions against yeast or mold contamination.
In contrast to the parabens and other anti-fungal agents, compounds prepared in accordance with the disclosure of U.S. Pat. No. 3,248,285 are not inactivated by nonionic emulsifiers, do not migrate from the aqueous to the oil phase, and are not deleteriously affected by other ingredients in the various preserved products. Unfortunately, the compounds heretofore prepared in accordance with the teachings of U.S. Pat. No. 3,248,285 exhibit only bacteriostatic and/or bactericidal activity. They do not exhibit adequate antimicrobial activity against yeast and mold. Parabens or similar compounds are, therefore, still required to adequately protect cosmetic and other perishable products even though they are susceptible to deactivation. Hence, there exists a need for a single compound which is effective against microbial contamination by yeast and mold as well as bacteria and which is easily incorporated into products, particularly cosmetic products, without suffering a significant reduction in activity.